The present invention relates to a lens module, etc., mounted on a portable telephone or the like and having a mode switching function.
Among small-sized camera modules used for portable telephones with a photographing function, surveillance cameras, etc., there appear camera modules with a mode switching function, by which a standard photographing mode (infinity mode) and a close-up photographing mode are switched in a simple way.
As a conventional technology described in publications and related to an improvement in operability of assembly of camera modules with a photographing mode switching function, there exists a technology of, for example, a camera module, which holds a lens to comprise a lens holder, a holder for holding the lens holder movably in an optical axis direction, and a regulating member fixed to an outer peripheral portion of the lens holder by means of an adhesive, and in which the outer peripheral portion of the lens holder is tapered to be decreased in diameter toward a subject (see JP-A-2005-195682).
Also, as a conventional technology described in publications and related to camera modules with a photographing mode switching function, there exists a technology of, for example, a camera, which comprises a cylindrical-shaped lead frame body with an optical unit received and held inside, a body internally threaded onto the lead frame body, and an image pickup device mounted to a bottom portion of the body, and in which the lead frame body is rotated to move axially in the body to change a focal distance of the optical unit, a plurality of thread ridges or thread grooves are formed circumferentially discontinuously and axially offset on an outer periphery of the lead frame body, thread grooves or thread ridges for threading with the multiplicity of thread ridges or thread grooves are formed on an inner periphery of the body (see JP-A-2005-157290).
Then, a camera module, in which a lens unit is threaded onto a barrel holding part, is sometimes changed in a threaded state by vibrations or the like. In such case, light outgoing from a lens could not appropriately form an image in an imaging region. In order to avoid such situation, a lens unit is threaded onto a barrel holding part to regulate image-formation and then fixed thereto by means of an adhesive or the like. With camera modules having a mode switching function, a barrel holding part is received and held in a state of being held by a spring and a spring presser to be movable in an optical axis direction. Therefore, a threaded state is changed by vibrations at the time of mode switching as well as by ordinary vibrations and so fixation with an adhesive is especially important.
However, it has been made difficult to ensure a space, into which an adhesive is injected, since threaded portions are closed by a spring presser according to a demand for miniaturization of a camera module in recent years.
Also, with camera modules having a mode switching function, mode switching is generally realized by changing a position (distance between an image pickup device and a lens) of a lens relative to an image pickup device. In order to move a position of a lens in a camera module and to fix the lens in a position after the movement, it is a simplest and reliable way to slide the lens relative to a reference plane.
In the case where sliding parts are present, however, abrasion dust generated by sliding enters a light receiving region and the abrasion dust could come out considerably in a picture.
On the other hand, when sliding parts are reduced so as to restrict abrasion dust as generated, a lens could also become offset in optical axis.